Lacrimal fluid covers eye ball surface consisting of cornea and conjunctiva to maintain wettability of the cornea and conjunctiva, and prevents drying. In recent years, however, an increasing number of people report various symptoms including feeling of fatigue and foreign sensation, namely, dry eye syndromes, which are caused by dry surface of cornea and conjunctiva due to decreased lacrimal fluid, dryness of eye during wearing contact lenses, or dryness of eye during operation of OA equipment and the like. Dry eye sometimes accompanies corneal epithelial disorder, corneal epithelial erosion and the like due to disorders of corneal epithelial cells. In a serious case, corneal ulcer and eye infection may be developed. To mitigate such various conditions caused by drying, artificial lacrimal fluids containing salts such as sodium chloride and the like as a main ingredient, eye drops containing hydroxyethylcellulose, chondroitin sulfate or hyaluronic acid and the like have been used. As the situation stands, however, there is no satisfactory agent as yet.
Lacrimal fluid is said to show pseudoplasticity. That is, the viscosity of lacrimal fluid decreases when a force is applied by blinking, and increases when the force is not applied. Therefore, lacrimal fluid has unique property in that it has low viscosity and becomes thin during blinking to facilitate blinking, but it becomes highly viscose before and after blinking to cover the eye surface for protection. As a polymer compound showing such pseudoplasticity, xanthan gum is known.
As an ophthalmic composition comprising xanthan gum, the following have been reported. For example, in patent reference 1, an ophthalmic composition containing echothiopate iodide and xanthan gum is disclosed, and xanthan gum has been reported to enhance the treatment effect of echothiopate iodide. In patent references 2, 3 and 4, an ophthalmic composition comprising xanthan gum and a carbonate dehydratase inhibitor has been disclosed, where xanthan gum is used to improve ophthalmic bioavailability of the carbonate dehydratase inhibitor. In patent references 5, 6 and 7, xanthan gum is used for the purpose of improving ophthalmic bioavailability of a drug, and an ophthalmic composition containing a carbonate dehydratase inhibitor and xanthan gum, or a prostaglandin derivative and xanthan gum, has also been disclosed. In patent reference 8, an ophthalmic composition containing quaternary nitrogen-containing ethoxylated glycoside and xanthan gum has been disclosed for the treatment of dry eye. In patent reference 9, an ophthalmic composition comprising xanthan gum, which is gelated upon contact with the eye, is disclosed. In patent reference 10, a pharmaceutical composition comprising xanthan gum as a re-epithelializing agent is disclosed.
In patent reference 11, an agent for suppressing the development of a corneal epithelial damage, which contains glucose as an active ingredient, is disclosed.
However, no report is found on an ophthalmic composition comprising xanthan gum and glucose. Moreover, it is not known that a corneal epithelial cell-protecting action can be improved by combining xanthan gum and glucose.    patent reference 1: U.S. Pat. No. 4,136,177    patent reference 2: JP-2001-508035    patent reference 3: JP-2002-501017    patent reference 4: JP-2002-506461    patent reference 5: JP-2002-501533    patent reference 6: JP-2002-521332    patent reference 7: JP-2002-521333    patent reference 8: JP-2001-516713    patent reference 9: JP-2002-510654    patent reference 10: JP-2005-529906    patent reference 11: JP-A-7-048262